Strange text changes in Mac Mail (not "predictive text")

I am having the same issue. Working on a long email I may delete entire paragraphs because I want to rework them, then as I am typing my new version, for reasons that aren't clear, suddenly Apple Mail will simply replace my new paragraph with the previously deleted version. Something odd is going on.

I am also having the same issue, since yesterday, with Sonoma 14.3. I was composing a long email, and the text kept changing to something I had already written in an earlier section of the email. Very confusing indeed.

I'm experiencing this exact same problem on two machines. One is a MacBook Pro M3 16" running Sonoma 14.3 and the other is a MacBook Air 14" M2 running Sonoma 14.0. The problem is somewhat intermittent and I have tested resizing the window as @BeaBenton suggested and that so far has seemed to resolve the problem, but I haven't tested this more than a few times. But this issue is absolutely maddening and makes the Mail app nearly unusable when it happens.

In response to the above 02/13/24 post about the recent update, macOS Sonoma 14.3.1, I turned predictive text back on and started a new test email in Mail. I put a lot of text in the email, made several experimental editing changes, and resized the window several times. So far I am no longer experiencing the odd text changes or text overlap events. Here's hoping that Apple fixed the issue with this update. I'll look forward to hearing if others have tested since the update to see if this issue is now resolved.

I'm having this problem too! When you say resize the window, are you making the new message window smaller or larger? I'll have a play but be good to know what you guys have found fixes the problem. Really hope they fix this bug soon. I like to keep the new message window quite small so I can sit it next to the message I'm replying to on the screen, and I've got it all set up how I like to work.... This glitch is going to make me change the whole blinkin' screen set up.

I haven't yet experienced the same issue in Sonoma, but I have predictive text turned off.

I know you said this isn't a "predictive text" issue, but I'm just curious--with the issue you are having, do you have "Show inline predictive text" turned off or is it still enabled? (System Settings > Keyboard > Text input > Edit)

https://appleinsider.com/inside/macos-sonoma/tips/how-to-use-or-disable-inline-predictive-text-in-macos-sonoma

Predictive text is definitely turned off. When I went googling how to fix, that's the first thing I tried. When I first googled the problem I couldn't find anyone having the same issue, and now it seems to be popping up more and more on forums. Guessing it's a bug from a recent update that's quite specific so only affecting some people, and hoping they'll send an update to fix it soon! In the mean time, if I'm typing long emails, I'm composing in Mac Pages and copying the text over to mail and just hitting send.

I have had the same issues since updating to Sonoma a week ago and it is doing my head in.

I also turned off predictive text (System Settings > Keyboard > Text input > Edit), but that did not change anything.

Resizing the window has stopped the text changing. (just dragging the side of the window out a bit). I did notice flickering sender names on the side menu whilst in mail, but that isn't a big issue (yet!).

I have this problem too, and my remedy has been to bring another window (from any app, including Mail) in front, and then bring back the message window. This indicates clearly (to me) that the mail text is not replaced, it's just a matter of how the text is drawn up (not sure of the correct term here) on the screen. Hiding and revealing the message window forces the text to be re-drawn.

I haven't tried resizing the message window but I will, and I'm sure it works since it (presumably) forces a re-draw.

BTW: flickering names in the mail list for me too.